SEM in the Spotlight: Imaging Invertebrates in Low-Vacuum Mode

By Ben Zink, Graduate Student, EFB

The following series of micrographs were recorded with the JEOL JSM-IT100 Scanning Electron Microscope under low-vacuum conditions. Traditionally, samples loaded into the SEM are covered with a thin coating of a conductive metal(s) such as gold/palladium or platinum. While this can be advantageous if the specimen is non-conductive and exhibits charging, surface detail can be hidden by the coating if it is too thick. This is where a major advantage to imaging an uncoated sample under low-vacuum conditions appears, chances of an artifact created during sample preparation are reduced. Series A is of a millipede (class Diplopoda), and Series B is of an ant (Formicidae sp.).

SEM in the Spotlight:

Ben Zink, Graduate Student, EFB

The new JEOL JSM-IT100 SEM at ESF offers many advantages over the previous, outdated model. With ESF being a university with the majority of its research environmentally and biologically related, a main advantage of the new microscope comes with its low-vacuum mode. This method of imaging allows the user to capture images of unfixed, uncoated specimens and is a major advantage when trying to image delicate biological specimens. The low-vacuum mode was demonstrated this semester to the EFB 496 class Biology of Lichens, taught by Dr. Alex Weir. Dr. Weir traditionally brings mycology related courses to the SEM lab as an introduction to electron microscopy and is an advantageous way to bring recognition to the NC-Brown Center. Lichens, being a fragile combination of algae and fungi, were a perfect candidate for a demonstration utilizing the low-vacuum mode. The following micrographs were captured from the lichen samples observed by the students during the demo.

This is an image of a gold crystal taken with the new JEOL JEM 2100F transmission electron microscope. Spacing of the lattice planes in the specially prepared gold crystals is a useful way to test the resolution and image stability of an electron microscope. This is one of the first images taken on our new TEM in Baker Lab at SUNY-ESF. The spacing in the planes of the crystal is approximately 2Å or 0.2 nm. An Angstrom (Å) unit is equal to 0.1 nanometer or 10-10 meters.

As many of you know, we received a National Science Foundation Major Research Instrumentation grant to support SUNY-ESF and partner institutions, Upstate MedicalUniversity and Syracuse University with new electron microscopes. The JEOL JSM IT100LA In Touch Scanning Electron Microscope was installed in January. The installation of the JEOL JEM2100FE transmission electron microscope is in progress.

Our two new electron microscopes were made possible through a grant from the National Science Foundation. The grant was award to a team of investigators from SUNY-ESF and partner institutions, Syracuse University and Upstate Medical University; Susan Anagnost, Ph.D., N.C. Brown Center Director and Principal Investigator on the grant, Robert P. Smith, M.S., and Ivan Gitsov, Ph.D., of ESF; Stephan Wilkens, Ph.D., of SUNY Upstate Medical University; and Mathew M. Maye, Ph.D., of Syracuse University. Funding for the microscope is also supported by Empire State Development’s Division of Science, Technology and Innovation (NYSTAR) and the three universities.

The Electron Microscopy Laboratory was established at the SUNY College of Forestry in 1955 as part of the Wood Technology Department, and was the first facility of its kind in Central New York, with the only transmission electron microscope in the area. This lab was established through the efforts of Dr. Wilfred A. Côté.

The N.C. Brown Center for Ultrastructure Studies was established in 1972 with the purchase of the center’s first scanning electron microscope. The purchase was made possible through funds left to the New York State College of Forestry Foundation, Inc. from the estate of Nelson C. Brown. Nelson Cortlandt Brown was a forester and faculty member from 1912-1917, and from 1921-1951 also served as Department Head of the Forestry department.

In addition to providing a unique research facility with initial focus on wood anatomy and ultrastructure, the center began to offer formal graduate level coursework in Light Microscopy and Photomicrography, Transmission Electron Microscopy, Scanning Electron Microscopy, Anatomy and Ultrastructure of Wood, and Interpretation of Cellular Ultrastructure. Today we continue to offer graduate coursework as well as an undergraduate minor in microscopy.

The image in our blog heading is a mosaic of wood “cubes” prepared by Mr. Arnold Day back in the 1970’s. These cubes were painstakingly prepared by sectioning with a sliding microtome the three surfaces; radial, tangential and cross section. Images were then acquired with the ETEC scanning electron microscope. These were featured on the cover of the book, Wood Structure and Identification by H. A. Core, W. A. Côté and A. C. Day, Syracuse University Press, 1979.